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Buried Wood Beds
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I couldn't remember if there's already a thread on this, and I couldn't find one, so here's this one, anyway.

I've had good success with burying wood below grade. My entire vegetable garden is done this way except where some semi-dwarf apple trees are planted. The garden is also heavily mulched in the paths with wood chips. The wood buried is a mixture of oak and juniper. I dug 18 - 24 inches down to "bedrock" - rocks too large to remove- and filled the trenches with wood, covering it with sifted soil. I still have to irrigate during the Summer to grow typical vegetables, but in my previous garden I was not able to keep the garden alive during the dead of Summer no matter how much I watered.

Some pics:

It took me a couple years to complete the garden. Here's a picture of part of the garden in Summer without buried wood:

Here's part with buried wood:

Both areas got the same amount of irrigation.

The garden this past October:

Please feel free to post pictures of your own buried wood beds. No typical hugelkultur or raised beds, please!

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I have been having great success with these too! The raised hugelbeets I've got are good for perennial herbs that like dry feet but the sunken ones work well for annual salad garden-y kinds of crops. I don't have nearly enough photos to do them justice but I think I can dig some up.

These are the beds where morels have been coming up along with a lot of other mushrooms and lots of good food. Experimental beds show a decided benefit to the buried wood when other variables are controlled for with cucumbers, green beans and salad greenss along with moisture loving herbs and flowers.

In one bed, on the opposite side of the garden from the others, rodents have moved in heavy duty and I let the chickens scratch up the mulch so some things didn't make it but the happy lavender that I am thinking of trying to save from winter chill with a homemade cloche is there. I figure the rodents' tunnels will be fertilizer and aeration so I haven't bothered them for now.
Thank you for sharing, Matu! So you have no problems with waterlogging in your moist climate? I've not had any problems with waterlogging even when the garden was flooded this past Spring, but I remember in earlier conversations with people about this technique,they worried about the beds waterlogging and becoming anaerobic.

I'm having trouble attaching photos! Our soil is on the sandy side, pretty well draining. One experimental bed is a buried wood kratergarden hybrid we built in the summer of 2014.

We buried wood on one side of the hole under a layer of goat/chicken straw bedding covered by a mix of compost and soil. It's a productive polyculture now, as well as being a microclimate and a view on drainage.
blue coco pole beans climbing through chicory
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kratergarden/hugellyhole hybrid
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Our soil is clay, but has a large number of earthworms, which I think keep the garden aerated.

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I'm always curious about the rate at which the soil drains so when I dig a hole for the buried wood I put the wood in fish buckets and five gallon buckets to soak (encouraging my little boys to pee in the soak water!) and I fill the hole with water, paying attention to how long it takes to seep. I was using to do this with the hole I plant trees and bushes into and I think it's a good idea. We do have good annual precipitation but recent years have had weeks upon weeks in a row of dry dry weather and this soaking is insurance against that. I've had thirsty cops go unirrigated and survive quite well when the needs without sunken wood shriveled. I'll dig around and try to find the comparison photos.
It's good advice to moisten the wood while you fill the hole. I also learned to add soil during the build process instead of just putting soil on top at the end, because if soil isn't sifted down between the logs, the bed will sink unevenly and spaces will form between the logs, which encourages mice. I had a lot of mice in the garden right after building the beds, but eventually the holes were filled as I added more material, and the mice disappeared.
I got some mice too, and then I got many snakes. At least 4 species in less than a quarter acre in one season this past summer

I am trying to upload a video I took this morning. No luck yet but I'll try again. It shows a couple of buried wood beds and a couple of raised ones.
I've done the same 'buried wood'. My soil is good but sandy, on a very pure sand subsoil. The last thing I need is 'better drainage', or a typical hugel. We have a lot of rain in winter, but our mediterranean summer is months of no water (PNW). Even after our recent/current typical winter downpour, soil is dry 6" down.

So I've worked on making my soil as water-retentive as I can, using all the tactics I can think of. Burying all organic material, of course, which includes wood in all it's forms; 'biochar' from Trader Joe's (ask me :); and clay, as in bentonite clay (ala cheapest kitty litter, from the feed store ... the 'clumping' variety holds more water) ..(also, Elliot Coleman recommends bentonite as a general beneficial soil amendment, citing German studies). (This is no for you, Tyler ;)

And then there's mulch... all wood chips, including hand-cut smallish clippings (not as difficult as it sounds!); and as many leaves (usually oak) as I can drag home in my small van (100 cans' worth this year / cheap plastic 32gal trash cans from Lowe's :). I could also mention sawdust, but I don't have a free source, so when I want some, I make do with $5 for 40lb wood pellets... which expand mightily, when wet, into a lot of lovely sawdust .... no additives, when I checked.

Climate change is bringing us hotter/drier summers here, and the water bill can get pretty high (I have 1/3 acre w/ house-garage in the middle :, so I'm trying to create a layer of 'sponge' stuff deep enough down to hold water through the summer. Oh, also... an idea I found and tried.... find non-color newspaper (don't listen Paul!), totally soak, form largish tight wads and put in bottom of the squash hill hole ;)

BTW, whenever I put wood/chips/dust/paper in soil, I complement the high carbon ratio with some strong nitrogen, ala the boys' pee ;)

Any more ideas that serve the function, along with 'wood' ?
Excellent report, nancy.

Next time I make a buried wood bed will be when I prepare planting holes for trees in my future food forest - I plan to put buried wood beds in the base of a basin/swale at each tree, and plan to include a lot of Prickly Pear cactus pads which are full of goopy sap. I can't remember who it was posted about putting cactus pads under their squash when planting. It seems like a good idea, and I have lots of cactus.
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I think of my buried wood beds as the water retention equivalent of thermal mass. They even out the wet and dry times.
I generally build beds with as many leaves as I can , topped with soul, and planted directly into.
I no longer build beds with wood branches and trunks alone, because of the rodent issue.
I now prefer to fill the gaps around the "unprocessed" wood with wood chips. I have done this as "paths" into my blackberry patch with great success.
No rodent issue, lots of mitochondrial action and always moist, not dry or wet.
I look forward to making biochar, but only if I can capture the heat for something.
I have several filled in pits that I use to call my biotrash pits. I suppose Hugelpit might be a better term nowadays. Some of the pits on my land were deep, big enough to literally swallow a car. Over the years I've been filling them in hugel-style. First to go in the hole were the cut up tree trunks and limbs. I then packed all sorts of organic debris in the holes and crannies, added a layer of dirt/manure, then watered it in. Then went on to filling the next layer. It took quite a while to fill in the big pits, but then again I was clearing some land and thus had lots of material on hand to use. Once a put was filled, actually mounded up to anticipate settling, I planted banana trees atop it.

On the years I get normal rainfall, I don't think the filled pits make a difference, but they don't waterlogged either because my land sits atop fractured lava. Plenty of drainage most of the place. But in drought years, the pits show their advantage. I have never had to water my banana trees, not even the year we got only 13 inches of rain. The trees thrived.

Each year I add a layer of horse manure covered with mulch around the bananas. And over the years the pits have sunk done. But I like this system because it works for me and my bananas.

Su Ba wrote:I have never had to water my banana trees, not even the year we got only 13 inches of rain.

Wow! That is a super endorsement, considering how much water banana trees are supposed to need! Fantastic!

Here is a link to an article which describes how we built some "hugelkultur" retaining wall terraces beds. They are working great.

Roof-Water-Fed Retaining Wall Hugelkultur Beds for the Dining Hall Patio
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#1 If there are no trees, and woody material is at a minimum, then it is probably not a cost effective use of your time.
That said, a lot can be done with small wood/brush.

Some of my thoughts on using hugulkultur in desert systems where some trees exist enough that removing them is not taking away from their ability to shade existing ecosystems:

I think that a key concerns is packing, or not, all spaces between the wood with soil or dense debris. The addition of air pockets, particularly in a hot desert situation, would definitely kill the water retaining principal of the system. it would also increase it's drainage potential, vastly.

Definitely, if hugulkultur is to be done in a desert environment, some portion of the wood should be below grade (and as the title and subject of the thread suggests, perhaps all of the wood should be below grade) Below grade the temperature is moderated, and moisture is retained easier.

It may be in the interest of people to have a trench above the bed to encourage water infiltration to the wood. Ditches and drainpipes should lead to it.

It could be on or under a swale.

The deeper and denser the wood below grade is, (and the wetter it is before incorporating in the bed) the more it can serve as a wick to bring capillary water upwards into the bed.

The soil has to have a given depth over the wood in order that the wood remain damp, thus enhancing the 'below grade' element.

If the bed is to be mounded at all, the larger the width of the bed (in direct ratio to it's height), the more soil surface contact to preserve moisture under the bed. This will also encourage a lens of downward water that will eventually (as perennial systems are established around the bed) join with the groundwater table.

Once a water lens has happened, and the symbiotic structure of fungal mycilia in the hugulbeds join with deep rooted desert trees (nitrogen fixers, shade providers) which are heading into deep sources.

Like when an orchard is planted, it takes a little while until the system really takes off, then all of the sudden it just goes boom. I think that this would be the same with hugulkultur in a desert environment. It may take a little longer than in a more temperate zone, and special considerations for evaporation/transpiration/and possibly deep aquifers should be observed.

Perhaps it should first be planted with a nurse species of local wild plants (especially nitrogen fixers and deep rooted shrubs) that will encourage the building of humus, and sourcing nutrients and water within and below the hugul.

Mulch. As deep as possible, on and around the bed.
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William Bronson wrote:
No rodent issue, lots of mitochondrial action and always moist, not dry or wet.

Okay, maybe it's me being picky, maybe spell check helped more than was wanted, but I wonder if I could get clarification on the "mitochondria" referred to here. To my knowledge, mitochondria are animal cell organelles. Is it micro-organisms that are getting all that action? Or am I about to learn some new thing discovered since I got a degree in field biology 40 some years ago?

yeah, probably mycelial or microbial, or BOTH in a healthy established hugel pit or mound.
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Thekla McDaniels wrote:

William Bronson wrote:
No rodent issue, lots of mitochondrial action and always moist, not dry or wet.

Okay, maybe it's me being picky, maybe spell check helped more than was wanted, but I wonder if I could get clarification on the "mitochondria" referred to here. To my knowledge, mitochondria are animal cell organelles. Is it micro-organisms that are getting all that action? Or am I about to learn some new thing discovered since I got a degree in field biology 40 some years ago?



I suck a spelling, and I failed to double check the spellcheck. I did intended to say mycelial action. Next time I will probably go with "fungus root action" which will be less than entirely correct, but still better than mitochondrial!
hey i was wondering if i could use your words and pictures to inform gardeners on my website raiseseeeds.com about this process.

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If you're talking to me, sure, you're welcome to!

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i was! thanks!

Raise Seeds

nancy sutton wrote:

So I've worked on making my soil as water-retentive as I can, using all the tactics I can think of. Burying all organic material, of course, which includes wood in all it's forms; 'biochar' from Trader Joe's (ask me :)

Okay, I gotta know! How do buy biochar from Trader Joes? :-o

How do buy biochar from Trader Joes?

I'm guessing: their hardwood lump charcoal? It is cheap enough to be a viable source.

Do we know how the Trader Joe's charcoal is produced? Is it an appropriate sustainable source of charcoal? Is charcoal the same as biochar?
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Is charcoal the same as biochar?

I can't speak for the Trader Joe's product (or answer your other questions reliably), Tyler, but from what I know any charcoal can be used to make bio-char; However, it is not bio-char on it's own. Bio-char is char with biology (usually nitrogen rich) added to it. Charcoal must be inoculated with compost, manure, urine, AACT, EM, fish waste, or some other thing that is nutrient rich in order activate it's potential and become bio-char. And this should be done before adding to the soil. Otherwise the charcoal on it's own will draw nutrients, especially nitrogen, from your soil until it has been charged to it's potential. Once a given lot of charcoal has been charged, it becomes an ongoing reservoir for nutrients via the resulting microbiological communities which thrive in the protection of the numerous cavities within the char bits. It also serves as both an aggregate for drainage, and a medium for retaining mini reserves of water. It becomes a source of humus production through it's microbial interrelation.

In addition, some charcoal is produced in a way that burns off too much of it's resins, which contain nutrients favored by some microbes and fungi, and so some might not be as good as some produced in a better way. I can't remember all the particulars, but will try to find a link to my main source of info on this.
This was the site that first got me interested in bio-char, and the simple backyard model in this article is basically what I built for my own project. The char making process takes just the right amount of time to make a perfect pot of organic long grain brown rice, and a stir fry!

I just did a quick scan search through that link I just posted, and although it is still full of awesome info, the specifics of what makes great bio-char, and what char does, is missing, as his homepage is under reconstruction. I'll try to find more stuff.
Thank you, Roberto. There's a forum for biochar, so I'll look there for more info.

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I posted this info in the 'Biochar in the Suburbs' thread.. mind you this is probably not 'perfect' biochar... but... ?

"If you aren't set up space, equipment or timewise to make your own charcoal, and then innoculate it, or don't have the $$ to buy a lot of commercial biochar, you might consider using an unusual form of charcoal. Typically bbq briquettes are verboten... Kingsfords, et al, are chock full of bad stuff. However, Trader Joe's BBQ Briquettes are advertised as 'sustainably harvested, with only cornstarch as a binder, and you can use the ashes in your garden!". They are approx $8 for 18 lbs. I did some research and found that this is the Rancher brand of 100% Natural Charcoal, made by The Original Charcoal Co., repackaged for TJ's. It is made from coppiced hardwoods grown in Latin American, i.e., sustainably."

I soak it in 'golden elixir' to 'bio charge' it :) I also added that I spent summer before last crushing it with a sledge hammer (whew!), but discovered last summer that it more or less 'dissolves' into small pieces if steeped a day or two. Plus, someone thought that 'chunks' worked fine.

I really hope the 'coppiced' part is true ;)

Thanks, nancy!

I am concerned about all the stuff going into the air from the burning of the 'firewood' used to roast the biomass into char (perhaps I misunderstand the process) The Top Lit Up Draft stove (google TLUD) eliminates the need for 'firewood' to heat the biomass.... you can google it, and find Art Donnelly's easy to make version.

And here's a thread about a really easy and interesting method... (no inner and outer containers, 'firewood', etc.)


....it is also described on other threads, using a commercial inverted metal 'cone', and in a Mother Earth News article on DIY biochar.. etc.

I think it is like the TLUD process, where, eventually, the pyrolysis gases from the uppermost layer of biomass are burning cleanly and 'roasting' the lower biomass layer, which then releases its gases to continue the burn, and lower and lower, etc, putting it out before gases run out and the charcoal begins burning So it's the released gases that generate the heat, and the biomass isn't heated to the point of becoming ash. And this is done in an open 'depression'... wow! ... . I think, anyway :) Is that confusing enough? :)

Thank you, Roberto. There's a forum for biochar, so I'll look there for more info.

No worries, Tyler. I didn't mean to hijack this cool thread onto the bio char tangent; just to answer part of your question.
Not a problem!

Yes, I guess I helped in the hijacking ;) But 'burying wood' might encompass charred wood.... ? The raw wood will, in time, decompose it's constituents back into volatile form.... I think? A long time, true. But if biochar truly comes from coppiced trees.... doesn't the regrowth continually remove CO2, and then sequester it for many decades (hopefully) in the soil, while also increasing water and nutrient utilization?

I'm still burying raw wood ('down-hugeling' ?), but find the biochar process fascinating. Sorry, Tyler, for conspiring in the shanghaing operation ;)
More discussion of buried wood and carbon sequestration here: http://www.permies.com/t/50725/hugelkultur/Hugelkulturs-Carbon-Sequestration

This might be the link to what you need Tyler. Now I'll stop.

Here's another project in which I'm using buried wood: http://www.permies.com/t/54118/forest-garden/Understory-Plum-Project
I'm wondering how long it would take to dig a buried hugel bed by hand. Does anyone have an estimate? Include some info about your soil and the size of the bed, please!
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